This invention relates to installation appliances for use with optic fiber, more particularly to such appliances that are spools having individual pockets for receiving such fiber.
Optic fibers are becoming an increasingly important transmission medium in high-speed electronic applications. Optic fiber is an extremely delicate material, however, and significant care must be taken in the handling of these fibers to prevent breakage, microcurves, and other distortions in the fiber that would inhibit transmission of data. Maintaining proper minimum fiber radii is an especially important aspect of optic fiber care. Bending the fiber below a minimum fiber radius can result in permanent damage to the fiber and in transmission losses. Fibers cannot be bent sharply into right angles and excess fiber in installations must be managed to avoid this damage.
Devices dealing with fiber bending and control issues have arisen primarily in regard to the field of optical fiber storage and shipping. Known methods of dealing with these issues include the use of traditional or slightly modified spools to minimize the bend in the fiber and the non-linearity that would result from such bends. Storage spools, as a result of their use as storage equipment have had to compromise ease of fiber maintenance to obtain greater capacity, some in excess of 200 m of fiber, arranging the fiber in multiple arrays, coiled one upon another. The issue of minimum bend radius is not exclusive to these large scale applications, but is also present in more confined conditions, for instance, connections between devices, such as related pieces of test equipment mounted in close proximity to each other, as in common or adjacent racks.
The following references may provide useful context for understanding the current state of the underlying technology.
Known spools may be composed of material designed to prevent thermal expansion and contraction that would damage the fiber.
One known solution to the problem of storing optic fibers without damage is to introduce slack into the fibers or padding the spool to prevent the fiber from being wound too tightly. There are various known means that have been used for introducing slack into the fiber to prevent it from being forced against the cylinder of the spool, from foam padding as in Myers U.S. Pat. No. 4,696,438 and Kim U.S. Pat. No. 5,971,316 to removable stays as in Lefevre U.S. Pat. No. 5,071,082. Myers ""438 uses a thin, 0.48 cm, layer of foam on a spool. Kim ""316 used foam pads and external shields on the barrel of the spool to absorb shock to the fiber that might occur in transport. Lefevre ""082 disclosed the use of a spool with indentations hollowed out along the barrel to accept rods that could be removed after the winding of the fiber, decreasing the tension.
Other known storage spool assemblies such as that disclosed U.S. Pat. No. 5,702,066 to Hurst, use clips to prevent the optic fiber from being forced against the barrel of the spool, thereby protecting against excessive bending or need to use fasteners such as tape or twist ties to keep the fiber from tangling or twisting. Such tangles and twists are to be avoided as they too might introduce microbends or kinks in the optic fiber.
Other known means of protecting optic fibers stored on spools from microbends and kinks include the development of means for more effectively winding the fiber on such a spool. Such variations include the development of bevels and groves in ancillary machines to guide the fiber during the winding process. Other external guide machines have been developed.
These spool storage technologies are not intended for holding live, signal carrying optic fibers between terminal devices. They fail to individually separate wraps of fiber for maintenance or replacement of individual fibers. Their construction is complicated by the multiplicity of the parts that they are comprised of, the materials they are composed of, and the complexity of their shapes.
Known systems have been used for the management of electrical and telephonic wires and fibers in field installations. These include the use of half spools 8, (FIG. 2) mounted perpendicularly to a flat surface 9 such as a wall, and more complicated wall mounted cabinets such as that disclosed in U.S. Pat. No. 6,175,079 to Johnson, that contains expandable spool sections and clips for controlling optical fiber. Half spools do not offer the same protection to the fiber and have similar disadvantages to storage spools. They fail to adequately control the fiber, allowing for damage, and do not allow the same orderly and easy maintenance of the fibers and a separated single fiber path. The difficult manufacture of more complex apparati, make such articles more costly, and installation, maintenance, and replacement more difficult.
Clearly a simple, relatively inexpensive, means for taking up excess optic fiber and properly managing and protecting that fiber, in which that fiber is readily accessible is necessary for use as an installation appliance in the fiber optic field.
It is an object of the invention to provide an installation appliance for preventing bends and damage in optical fiber installations, caused by bends in the fiber tighter than the minimum radius.
It is a further object of the invention to provide a means for controlling lengths of optical fiber longer than necessary for the terminal connections required.
It is yet further object of the invention to provide an installation appliance of spool like shape with individual channels for each coil of optical fiber.
It is another object of the invention to provide a means of facile service and maintenance of installed optical fiber.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein I have shown and described only a preferred embodiment of the invention, simply by way of illustration of the best mode contemplated by me on carrying out my invention.